难度Ｂ／Ａ级
Air Pollution Cloud Measured on Both Sides of Pacific
    Scientists watched closely last spring as a haze of pollution, which had been tracked by  satellite as it crossed the Pacific Ocean，settled over a large swath of North America from Calgary, Canada，into Arizona．Now it appears that，for the first time, researchers on both sides of  the Pacific took detailed measurements of the same plume，a cloud that contained Gobi desert dust as well as hydrocarbons from industrial pollution．
    Heather Price，a University of Washington doctoral student in chemistry, found that the amount of light reflected by the particles in the air was more than 550 percent greater than normal for that time of year．The mass of Asian air contained elevated levels of all pollutants measured．
Price said，“but the only thing that came close to being alarming was the level of particulate Matter.”
    The haze that settled across the western part of the country was widely reported by the news media，and it was measured as far inland as the ski slopes of Aspen, Colo.
Readings on the western side of the Pacific came from the Aerosol  Characterization Experiments, a project aimed at understanding how particles in the atmosphere affect Earth’s climate. Additional measurements were taken in the same region at the same time under a project sponsored by the National Aeronautics and Space  Administration．
    Knowing the pollution was approaching Washington state，Price loaded sensing equipment aboard a rented Beechcraft on April 1 4 and flew to Neah Bay on the state’s Northwest coast．Taking samples at various levels from 15，000 feet to 20，000 feet in altitude，she monitored
quantities of dust，ozone，carbon monoxide and hydrocarbons．“From my copilot’s seat．the dust
was thick enough to see with the naked eye．”Price said．
Now she’s trying to correlate her findings with those of the two research teams operating on the other side of the Pacific，where at one point the pollution plume was larger than Japan．The huge size of the cloud showed up clearly in satellite images that gave Price plenty of warning the haze was on its way．“You can see these two blobs coming out of the deserts of Mongolia and growing over Asia，then getting swept out over the ocean and finally setting over North America,”
she said. She intends to continue measuring air samples off the Washington coast and will be looking for air masses with evidence of pollution originating somewhere other than Asia. “We’d
like to see if we can get a signature of pollution coming from Europe because computer models suggest that European sources also can be transported across the Pacific，” she said．“However, we
expect that sources in Europe will contribute less than Asian sources．”

练习：
1.The haze of pollution mentioned in the first paragraph is a cloud
A) of moisture over Calgary, Canada．
B) developing over Pacific Ocean．
C) of industrial pollutants．
D) of desert dust and hydrocarbons．

2.One of the Prices’S findings (Paragraph 2)about the particles of the air is that
A) they contain more pollutants than normal particles．
B) they move much faster in high altitudes than in low altitudes．
C) they are finer and lighter than normal particles．
D) their ability to reflect light is much than stronger．
  
3.What did Price not do during her research?
A) She rented a Beechcraft．
B) She used her sensing equipment aboard the Beechcrah．
C) She collected samples of pollutants on the Northwest coast for further tests．
D) She tested quantities of chemicals in the air．

4.According to the last paragraph，which of the following statements about the two research
    teams is true?
A) The two research teams whose findings Price correlates hers with are based in Asia．
B) Price corrects some inaccurate data provided by the two teams operating in Asia．
C) Price is working with the two research teams in Japan．
D) The two teams in Asia volunteer to correlate their findings with Price’s．

5.Which of the statements is closest in meaning to the sentence“…，we expect that sources in
  Europe will contribute less than Asian sources．”?
A) Pollution is expected to be less serious in Europe than in Asia．
B) Pollution is studied in more depth in Europe than in Asia．
  C) Pollutants coming from Europe are not the main source of pollution in North America．
D)Pollutants coming from Europe are the main source of pollution in North America．